3Ware 9550SXU-12 User Manual page 332

Glossary
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• . The size of the data written to each disk drive in RAID unit
Stripe size
levels that support striping. The size of stripes can be set for a given unit
during configuration. In general, smaller stripe sizes are better for
sequential I/O, such as video, and larger strip sizes are better for random
I/O (such as databases). The stripe size is user-configurable at 64KB,
128KB, or 256KB.
This stripe size is sometimes referred as a "minor" stripe size. A major
stripe size is equal to the minor stripe size times the number of disks in the
unit.
• The process of breaking up files into smaller sizes and
Striping.
distributing the data amongst two or more drives. Since smaller amounts
of data are written to multiple disk drives simultaneously, this results in
an increase in performance. Striping occurs in RAID 0, 5, 6, 10 and 50.
• A logical unit of storage that is part of another unit. For
Subunit.
example, the mirrored pairs (RAID 1) in a RAID 10 unit are subunits of
the RAID 10 unit.
• UDMA mode. UDMA mode is a protocol that supports bursting data up to
133 MB/sec. with PATA disk drives. This protocol is supported for earlier
versions of 3ware RAID controllers, however it is not supported for
SATA or SAS drives on newer controllers such as the 9690SA series.
• Unit ID . A unique identifier for a specific unit in a system.
• . The SCSI number, or channel number, of a particular unit.
Unit Number
• . A logical unit of storage, which the operating system treats as a
Unit
single drive. A unit may consist of a single drive or several drives. Also
known as an array.
• Verify . A process that confirms the validity of the redundant data in a
redundant unit. For a RAID 1 and RAID 10 unit, a verify will compare the
data of one mirror with the other. For RAID 5, RAID 6, and RAID 50, a
verify will calculate RAID 5 parity and compare it to what is written on
the disk drive.
• The 3ware 9690SA RAID controller has 128 addresses available
VPort.
to assign to hard drives. These addresses are known as virtual port (vport)
IDs. By using vport IDs and expanders, one controller phy can connect to
multiple drives. This is in contrast to standard port connections which are
one-to-one physical connections.
• Wide Port . A SAS port can consist of one or more phys. When a SAS
port consists of one phy it is known as a narrow port, when it contains
multiple phys it is known as a wide port. The 3ware 9690SA controller
has two wide port connectors that contain 4 phys each. These phys can
function individually, in which case each phy has its own SAS address, or
the 4 phys can be banded together, in which case they share the same SAS
address. A 9690SA wideport can have a bandwidth of up to 12.0 Gbps.
3ware SAS/SATA RAID Software User Guide, Version 9.5.1